Steam generator



Jan. 26, 1932. F. DUFFIELD STEAM GENERATOR Filed Oct. 20, 1928 4 Sheejs-Sheet 1 Jan. 26, 1932. F. DUFFIELD STEAM GENERATOR Filed Oct. 20, 1928 4 Sheets-Sheet 2 R w 0 F T m 0 V W N A m m T J M 0M .m

Jan. 26, 1932.

-F. L. DUFFIELD STEAM GENERATOR Filed Oct. 20, 1928 4 Sheets-Sheet 3 W W ffiv By TBuLMm 3: 'Tbubmm Jan. 26, 1932. ,F. DUF-FIELD 1,842,935

STEAM GENERATOR Filed oci. 20, 1928 4 Sheets-Sheet 4 Fig.5. FL .8. M10.

'INVENTDR By Tuuhwlu (Tuuhvxin ATTDRNEYi V I mm m o Patented Jan. 26, 1932 UNETED STATES PATE r time FREDERICK LINDLEY DUFFIELD, OF LONDON, ENGLAND STE-AM GENERATOR Application filed October 20, 1928, Serial No. 313,834, and in Great Britain October 22, 1927.

This invention relates to steam generators and more particularly to water tube boilers.

The object of this invention is to provide means for effecting a maximum degree of heat transmission from the heating medium to the fluid under treatment without employing an economizer.

In a water tube boiler made according to the present invention means are provided for causing a slow movement of the feed water in the water tubes for a part of their length and for causing a rapid mover .ent of the water in the remaining parts of their length.

Gne way of carrying out the present in vention is illustrated by way of example in the drawings filed herewith, wherein Fig. 1 is a part elevation and part section of one form of boiler made in accordance with this invention.

Fig. 2 is a section.

Figs. 3 and 4: are sections.

Fig. 5 is a plan of a field tube adapted for use in steam generators made in accordance with this invention.

Figs. 6 and 7 are front and end views of a modified form of field tube.

Fi g. 8 is a front view and Fig. 9 a plan view of the modified tube complete with the guiding device, and

Fig. 10 is a View of the field tube shown in position in the usual water tube.

Referring to Figs. 1-5 of the drawings, vertical connecting tubes 0 c are disposed be tween the top headers a a and the bottom' headers Z) l). The tubes 0 0 are protected by two semicircular refractory outer linings resting on a collar piece on the tubes as shown in Fig. 1. In the boiler shown the hot gases proceed from the burner 11 and pass downwardly between the rows of tubes 0 into the air heaters 12, which supply the air for combustion. The zone of greatest heat is therefore at the top of the tubes 0 0.

Field tubes d (Z are disposed within the tubes 0 0 and extend downwards a partial distance from the top of the connecting tubes 0 0, which open into the top headers.

Detail views of the field tubes 03 d are illustrated in Figs. 6-10 filed herewith.- In these figures it will be seen that the field tubes d are flattened out towards the top, the topmost portion consisting of two separate flat extensions Z. Two approximately semicylindrical plates m are welded or otherwise fixed to the edges ofthe members Z, and this combination of the members Z and m constitutes a guide as will hereafter be fully explained. These guides are illustrated in Figs. 1 and 2 and are markede, and it will be seen that they project intothe headers a. 'The tubes 0 are flared at top as shown at p to form a seat adapted to rest against the base of the headers a. The field tubes 0? are formed at their lower ends with a number of outwardly curved members or guides 0, the purpose ofwhich is to'position the tubes (Z centrally in the tubes 0. The steam from the top headers a is conveyed to steam drums g g, and the bottom headersare connected withieed water drums whose level corresponds to the level within water of condensation in the headers 44 passes down through the passage formed between the members 6, then down through the field tube-s. When this water reaches the bottom of the field tubes it turns outwards and upwards, mixing with the water and steam in the tubes 0, and is ejected into the headers a through the guides a above the flow of water for downward circulation within the field tube, so that the upward outer flow does not obstruct or in any way interfere with the in take for the inner downward flow.

By the use of the present invention there is set upa rapid circulation over that vicinity of the tube to the distance to which the field tube exists, and a very slow movement of the water takes place in the lower portion of the tube which does not contain the field tube. By this differential movement there is established a hotter liquid flow at the top than at the bottom of the tube, which corresponds with the heat gradient of the gases (viz. the heating medium) the gases also being hotter at the top and cooler at the bottom, thus enabling a greater degree of heat transmission by reason of the maximum relative difference in temperatures being maintained between 5 the heating gases and the liquid undergoing heating.

Vhat I claim and desire to secure by Letters Patent is 1. In a Water tub-e boiler comprising a 10 steam drum, a series of top headers arranged beneath and transversely to the steam drum, a series of bottom headers, Water tubes c011- necting the top and bottom headers burners disposed between the top headers, combustion chambers disposed between the water tubes and communicating with the burners, and field tubes disposed within the water tubes for a portion of their length, extensions to the water tubes the said extensions being carried on the field tubes and projecting into the top headers, so that the incoming steam and hot water enters the top headers above the level of the water of condensation therein which is drawn off and returned to circulation through the field tubes.

2. In a water tube boiler comprising a steam drum, a series of top headers arranged beneath and transversely to the steam drum, a series of bottom headers, water tubes con- 30 necting the top and bottom headers burners disposed between the top headers, combustion chambers disposed between the water tubes and communicating with the burners, M and field tubes disposed within the water tubes for a portion of their length, means for centering the field tubes within the water tubes, Xtensions to the water tubes, the said extensions being carried on the field tubes and projecting into the top headers, so that the incoming steam and hot water enters the top header above the level of the Water of condensation therein, which is drawn oil? and returned to circulation through the field tubes. In testimony whereof, I atfix my signature.

FREDERMIK LINDLEY DUFFEELD. 

